There has been developed an AC/DC electric railcar that can run both in an AC section where an AC voltage is supplied from, for example, an overhead wire, and in a DC section where a DC voltage is supplied from, for example, an overhead wire. Some conventional electric railcars may, for example, have a structure in which a reactor is arranged singly and separately from a transformer, and some may have a structure in which a transformer and a reactor are accommodated in a single-piece tank. In such AC/DC electric railcars, however, an apparatus for an AC section, such as a transformer, cannot be used in a DC section, and to the contrary, an apparatus for a DC section, such as a reactor, cannot be used in an AC section. Consequently, both of the apparatus for an AC section and the apparatus for a DC section are needed, however, there may be the difficulty in equipping such an AC/DC electric railcar with both of the apparatuses in the limited space, such as under the floor of a carbody.
Here, Japanese Patent Laying-Open No. 03-038807 discloses a shared shunt reactor type transformer unifying a transformer and a shunt reactor, which is formed of a bypass core provided at a portion of a yoke of the transformer and a gapped core and a reactor coil provided within the space surrounded by the portion of the yoke and the bypass core. Further, the bypass core forms a yoke of the reactor, as well as the winding direction of a coil of the transformer and the winding direction of a coil of the shunt reactor are directed such that the transformer magnetic flux in the portion of the yoke and the reactor magnetic flux cancel each other out.
Further, Japanese Patent Laying-Open No. 11-273975 discloses a common mode choke coil that is formed of first, second, third, and fourth coils of edgewise-wound rectangular wires, and a magnetic core forming a closed magnetic path in the shape of a hollow square. Further, the first and second coils are arranged at one magnetic leg of the magnetic core, the third and fourth coils are arranged at the other opposite magnetic leg, and the first and third coils as well as the second and fourth coils are connected in series. Line current cancels the magnetic fluxes generated at the first and second coils, the second and third coils, the third and fourth coils, the fourth and first coils, and urges the magnetic fluxes generated at the first and third coils and the second and fourth coils each other. Furthermore, the winding direction of each coil is set so that the respective magnetic fluxes generated at the first, second, third, and fourth coils are urged by current flowing in the same direction, the first and fourth coils are arranged in parallel, and the second and third coils are arranged in parallel.
Patent Document 1: Japanese Patent Laying-Open No. 03-038807
Patent Document 2: Japanese Patent Laying-Open No. 11-273975